MEC 2 MICROPROCESSOR ENGINE/GENERATOR CONTROLLER
PM056 Rev 6 05/10/15 Thomson Technology
5
ground. The MEC 2 is internally protected by a solid state type fuse that protects it from
internal short circuits. The solid state fuse will automatically reset when the over current
condition is removed. Wiring from the engine cranking battery to the control panel should
conform to the following guidelines to avoid possible controller malfunction and/or
damage.
2.2.1. Avoid wiring from the engine starter terminals - wiring should go directly
from the battery terminals to the engine control panel (to avoid voltage drop in
the starter cables and starter motor commutator noise). Note: Unit mounted
control panels with short wiring runs may utilize connections from the starter
terminals provided that the specific application is tested satisfactorily.
CAUTION!!!
The battery charger must be turned off before battery cables are
removed from the battery (i.e. for servicing). Failure to do so may
subject the control panel to an over voltage condition in which
damage may result.
2.2.2. Wiring from battery to engine control panel should be two - #14 AWG
(2.5mm
2
) wires (i.e. do not use the engine block as one of the common
conductors).
2.2.3. Under noisy environments (i.e. gas engines with high voltage ignitions,
etc.), wiring from battery should be a twisted pair of #14 AWG (2.5mm
2
) wires.
2.3. SPEED SENSING INPUT
Field wiring of the speed sensing signal wires should conform to the following guidelines
to avoid possible controller malfunction and/or damage:
2.3.1. Wiring from magnetic pickup must utilize a 2 conductor shielded/twisted
cable. The drain (shield) wire must be connected at the control panel end only.
2.3.2. Magnetic pickup voltage at cranking
speed must be greater than 3.0VAC.
At nominal
speed, magnetic pickup voltage should be between 3 and 5VAC.
2.3.3. A single dedicated
magnetic pickup is recommended for connection to the
speed sensing input terminals. Note: One common magnetic pickup may be
utilized for the system provided specific test measurements are done with the
equipment installed (i.e. mag pickup voltage levels meet the required levels).
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